Muzan Kibutsuji

Muzan appears to be a twenty-year-old man. He has short, wavy black hair and red eyes. Muzan dresses rather extravagantly, most often wearing a white shirt, a black jacket, white trousers, a white tie, and black shoes with small heels. In his demon form, his nails are usually long and sharp, dark blue. The manga depicts his ability to change his appearance. His height is 179 cm.

Due to his apparent superiority and two-faced nature, he feels little affection for his minions, using and discarding them as disposable pawns as he pleases. He does not allow his subordinates to question his will, regularly using brutal repression. Many of his subordinates, in turn, deeply fear him and watch their words and thoughts carefully, afraid to say anything that might upset him. They cannot even dare to think anything that might be perceived as hostile by Muzan, as he is able to read the minds of all the Moons. He is able to sway many demons to his side with promises of power, revenge, and greatness so long as they serve him. His intellect and manipulation shine here, as many find these promises quite appealing, as he encounters many of his subordinates at their lowest point, when their emotions are easily fed for him. Unfortunately, all of these promises are ultimately false, given that Kibutsuji only cares about himself and has no qualms about killing his own people to protect his own safety.

His inflated ego and delusional sense of self-importance are so great that he cannot tolerate being mocked or corrected, believing that others exist only to serve him. This also means he rarely takes any opponent or threat seriously. He brutally murdered a pair of drunk men simply for being rude to him, and killed their companion even though she did nothing, all while proclaiming his own perfection and superiority over them. When he finally confronted Kagaya Ubuyashiki, the man responded to Muzan with a tone of pity and sadness for the life he had led. In Muzan's mind, this was registered only as insults and threats, which he used to justify his hatred of Humanity and the Demon Slayers.

While Muzan was still in his mother's womb, his heart stopped several times. He was born without a pulse and did not breathe, which is why he was considered stillborn, and only let out his first cry when he was about to be cremated.

When Muzan was a young man, he was diagnosed with a disease that would cause him to die before he reached the age of 20. The doctor treating Muzan gave him a prototype of a cure, but Muzan, angry that his condition was getting worse, killed his doctor. He later realized that the cure actually worked, and his body became stronger. It was easy for him to eat people to survive, but he faced another problem: he could not be in the sun. Because sunlight was now deadly to him, Muzan was forced to live a nocturnal lifestyle, which made him very angry. At this point, he deeply regretted killing the doctor before he finished developing the cure, called the "blue spider lily." Muzan searched all over the country for the spider lily, which was part of the cure, but could not find it, so he began to create more demons. He wanted to spread demons throughout the world, hoping that one of them would eventually be able to defeat the sun, or at least find the blue spider lily, so that Muzan could become a perfect being.

About 400 years before the manga's plot, Muzan met Tamayo, who was ill. Muzan turned her into a demon.

One day, a demon hunter who possessed the breath of the sun almost killed Muzan, but the man survived and henceforth became more careful with all people who possessed or could possess this breath. The distinguishing feature of these people were hanafuda earrings.

Muzan later decides to create a group of twelve of the strongest demons, dubbing them the "Twelve Demon Moons" for his potential protection and uniting them with two goals: eliminating all demon hunters and also finding his treasured cure.

Extrasensory perception: Kibutsuji is able to sense the presence of other demons or someone's thirst for blood.

Poison Resistance: His body is much more resistant to the poison from wisteria, which is fatal to normal demons.

Regeneration: Muzan can continue to live even if his body or head is completely destroyed.

Absorption. Muzan can devour other demons, people, or objects.